Method and device for packing products in films and film-packed product

ABSTRACT

The present invention is directed to a method of wrapping products in films, including the steps of: positioning the products on a first sheet of film which is continuously advanced in one transport direction; covering the products with a second sheet of film, which is continuously advanced in the transport direction and which is aligned plane-parallel to the first sheet of film; ultrasonically welding the first and second films on the outer edges of the products in each case and ultrasonically separating the overlapping films at selected positions; separating the wrapped products or groups of wrapped products.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Stage of application PCT/EP03/07763 filedon Jul. 17, 2003 claiming priority to DE 102 32 330.5 filed Jul. 17,2002.

TECHNICAL FIELD

The invention relates to a method of wrapping products in films,comprising the steps of: positioning the products on a first sheet offilm which is continuously advanced in one transport direction; andcovering the products with a second sheet of film, which is continuouslyadvanced in the transport direction and which is aligned plane-parallelto the first sheet of film. The invention further relates to a devicefor wrapping products in films in accordance with such a method, and toa film-wrapped product, especially confectionery, which is wrappedbetween two films.

BACKGROUND OF THE INVENTION

Products, especially confectionery such as sweets, chocolates, etc., areconventionally wrapped in wrapping paper. This involves the disadvantagethat the product is not wrapped hermetically until the time ofconsumption.

It is also known to wrap products in films which are plasticized andwelded by the application of heat. As a consequence of the heatingeffect, there is a risk that the product could be affected as well andthat it could melt, at least in parts.

Sensitive products are conventionally wrapped by bonding films together.This is relatively complicated, especially because the adhesive has tobe applied thinly and evenly to the bonding sites. Furthermore, theadherents are relatively large.

The object of the invention was therefore to provide an improved methodand an improved device for wrapping products in films, in order inparticular to make economical mass production possible and to obtainhermetically wrapped products.

BRIEF SUMMARY OF THE INVENTION

The object is achieved in accordance with the invention, using thegeneric method, by the steps of:

ultrasonically welding the first and second films on the outer edges ofthe products in each case and ultrasonically cutting the overlappingfilms at selected positions, and

separating the wrapped products or groups of wrapped products.

Unlike the conventional film wrappings for products, it is now proposedthat the film be bonded together by ultrasonic welding at the outeredges of the products. In the process, the overlapping films can be cutultrasonically at the same time at selected positions, and theindividual wrapped products separated from each other.

The ultrasonic welding and ultrasonic cutting can be performed at a highclock rate on a wrapping line, with the products being positionedbetween two continuously advanced sheets of film.

The ultrasonic welding and separation process is preferably performedwith a supporting table aligned plane-parallel to one of the films foran adjacent sheet of film. Opposite the supporting table andplane-parallel thereto, a welding punch is disposed above the othersheet of film, the welding punch being moved towards the supportingtable to perform the ultrasonic welding and separation. By exciting thewelding punch and/or the supporting table with ultrasonic oscillationsand pressing the films together on the supporting table at the weldingand cutting edges with the welding punch, defined welding seams andcutting edges are then created.

It is particularly advantageous if the supporting table has anintegrated sonotrode device to generate an ultrasonic oscillation on thesurface of the supporting table. The films are then pressed onto thesupporting table in the region of the welding and cutting edges of thewelding punch, which is not excited. The welding and cutting edges arean image of the welded and cut edges of the wrapped products.

In this way, it is possible to produce the welding punch relativelyinexpensively for various products, since no sonotrode arrangement needsto be integrated into the welding punch and the propagation conditionsof the ultrasound waves, which are dependent on the shape of theindividual product, do not have to be taken into account when designingthe welding punch. Instead, a universal supporting table with anintegrated sonotrode arrangement can be used for any shape of thewelding punch. In this way, the tooling costs and set-up work canadvantageously be reduced.

In addition, it is advantageous to pre-shape at least one film toreceive the products before the step of positioning the product on thesheet of film. In the process, indentations can be introduced into thefilm be thermal, mechanical, or vacuum shaping or the like, in order toreceive the products. The problem is further solved by the genericdevice in accordance with the invention with:

a first conveyor means for continuously advancing a first sheet of film,

a positioning means for positioning products on the first sheet of film,

a second conveyor means for covering the products positioned on thefirst sheet of film with a second sheet of film, which is alignedplane-parallel to the first sheet of film,

a fixed supporting table with an integrated sonotrode arrangement forgenerating ultrasonic oscillations and

an opposing welding punch disposed plane-parallel to the supportingtable, the welding punch having welding and cutting edges as an image ofthe welding and cut edges to be produced in the wrapped products.

The welding punch is mounted on the supporting table such as to movetowards and away from the supporting table. The sheets of film with theproducts held between them are guided between the supporting table andthe welding punch.

By pressing the welding and cutting edges of the welding punch onto thesupporting table and exciting the supporting tables with ultrasonicoscillations, defined welding and cutting seams are produced on thewelding and cutting edges of the overlapping sheets of film.

The device preferably also has at least one pre-shaping means forpre-shaping at least one of the film walls such that the products can bereceived in indentations in the pre-shaped films.

The welding and cutting edges of the welding punch are preferably shapedin such a way that a pull-tab is formed on an outer edge of the productwrapping and the first and second films are not welded together in theregion of the pull-tab.

The problem in ultrasonically sealing products in films consists in thefact that, even with very narrow welding seams, the latter are stable.

It has further become apparent that it is possible to tear open anultrasonically welded product wrapping without undue force if a weldingseam or cut line runs transversely from the pull-tab into the weldingseam on the outer edge of the product wrapping. The welding and cuttingedges of the welding punch are therefore preferably shaped in such a waythat a welding seam or cut line of this kind running transversely intothe welding seam on the outer edge of the product wrapping is formed.

In addition, it is advantageous if the welding and cutting edges of thewelding punch are formed in such a way that a cut line between two outeredges of the product wrapping runs transversely across one of the filmsof the product wrapping. When the product wrapping is bent over alongthe cut line, the product wrapping breaks open at the cut line, whichforms a defined breaking point.

The object is further achieved by a film-wrapped product, especiallyconfectionery, in which the films are ultrasonically welded togetheralong the entire outer edges of the product and at least one pull-tab isprovided at an outer edge.

The film-wrapped product preferably has a welding seam or cut line inthe pull-tab, which runs transversely into a welding seam at the outeredge of the product wrapping, so that the welding seam can be separatedat the outer edge without undue effort.

Preferably, the film-wrapped product also has a cut line between twoouter edges of the product wrapping, which runs transversely across oneof the films of the product wrapping.

In a particular embodiment, especially when it is a question ofproducing prototypes of product wrappings, it is proposed to provide amovable pressure roller above the supporting table, which can be guidedacross any sheets of film in a controlled manner and with a definedpressure. In this way, contours for ultrasonic welding and/or ultrasonicseparation can be traced out with the pressure roller in a freelyselectable manner.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theattached drawings, in which:

FIG. 1 shows a perspective schematic view of a device for wrappingproducts in films in accordance with the invention;

FIG. 2 shows a perspective view of a different embodiment of a devicefor wrapping products in films in accordance with the invention;

FIG. 3 shows a top plan view of a film-wrapped product with a pull-tab;

FIG. 4 shows a cross-sectional view of the film-wrapped product fromFIG. 3;

FIG. 5 shows a top plan view of a film-wrapped product with a pull-taband a seam running transversely to the outer edge;

FIG. 6 shows a top plan view of a film-wrapped product with a cut linebetween two outer edges; and

FIG. 7 shows a side plan view of a portion of a different embodiment ofa device for wrapping products in films in accordance with theinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 illustrates a first embodiment of a device for wrapping products1 in films 2 a, b in a schematic perspective view. The strips of film 2a, 2 b are continuously unrolled from a roll and are each advanced by aconveyor means. The products 1 on product supports 3 are transported tothe first sheet of film 2 a and positioned on the first sheet of film 2a by means of a positioning device 4. For this purpose, the positioningdevice 4 is equipped with suitable gripped means so that it may serve asa handling device. After the products 1 have been positioned on thefirst sheet of film 2 a, the products 1 are advanced further in thetransport direction and covered with the second sheet of film 2 b. Forthis purpose, the second sheet of film 2 b is aligned plane-parallel tothe first sheet of film 2 a.

The second sheet of film 2 b is pre-shaped by means of a pre-shapingmeans 5 in such a way that indentations are created in the film toreceive the products accurately. To align the indentations to theproducts accurately when the second sheet of film 2 b is placed on theproducts 1 and the first sheet of film 2 a, an equalizing roller 6 isprovided.

After the products 1 have been covered by the second sheet of film 2 b,ultrasonic welding and ultrasonic cutting are performed. For thispurpose, a supporting table 7 is provided beneath the first sheet offilm 2 a, in which a sonotrode device to generate an ultrasonicoscillation is integrated. Disposed opposite the supporting table 7 is awelding punch 8 which is aligned plane-parallel thereto and is mountedsuch as to move towards the supporting table 7 and away from thesupporting table 7. The welding punch 8 has raised welding and cuttingedges, which are an image of the welded and cut edges to be produced inthe wrapped products.

The welding punch is pressed firmly against the welding and cuttingedges on the supporting table 7, so that the overlapping films of thesheets of film 2 a, 2 b are excited by the ultrasonic oscillation of thesupporting table 7. In the process, a very stable welding seam or cutedge is produced, depending on the design of the welding and cuttingedges of the welding punch 8.

In this context, the welding punch 8 is designed to be independent ofthe specific product, thanks to the welding and cutting edges. Using theuniversal supporting table 7 with an integrated sonotrode device, it isnow possible to produce and provide the welding punch 8 as a replaceabletool relatively inexpensively for various product shapes.

After ultrasonic welding and separation, the second sheet of film 2 b,reduced by the portions welded to the first sheet of film 2 a in orderto wrap the products 1, are rolled up again and the wrapped products areseparated.

FIG. 2 illustrates a different embodiment of a device for film-wrappingproducts 1 in accordance with the invention, in which the first sheet offilm 2 a is pre-shaped with a pre-shaping means 9 in such a way thatindentations to receive the products 1 are formed. Pre-shaping can beperformed by thermal means, for example, by vacuum drawing, or by someother shaping process. FIG. 2 shows a sketch of a pre-shaping means 9with a semi-flexible moulding base and a moulding press capable of beingmoved relative to the moulding base.

Seen in the transport direction, a positioning device 4 is disposeddownstream of the pre-shaping means 9 to position the products 1 on thefirst sheet of film 2 a. In the embodiment illustrated, the positioningdevice 4 is designed as a filling means, in order to fill the product inthe indentations created in the first sheet of film 2 a. The product 1can in this case be a piece of confectionery, for example, andespecially a solid piece of chocolate.

The first sheet of film 2 a, with the product 1 filled in theindentations, then passes through a cooling section 10. After that, asecond sheet of film 2 b, which is aligned plane-parallel to the firstsheet of film 2 a, is placed over the first sheet of film 2 a. For thispurpose, the second sheet of film 2 b is continuously unrolled onto thefirst sheet of film 2 a and completely covers the product 1 filled inthe indentations.

Disposed above the second sheet of film 2 b is a supporting table 7 withan integrated sonotrode device, generating ultrasonic oscillations.Opposite the supporting table and movable relative to it is a weldingpunch 8 with welding and cutting edges each abutting the outer edges ofthe indentations formed in the first sheet of film 2 a. When the weldingand cut edges of the welding punch 8 are pressed against the supportingtable 7, with the first and second sheets of film 2 a, 2 b with theproduct 1 filled in being located between the supporting table 7 and thewelding punch 8, the ultrasonic oscillations are directed through thefirst and second films 2 a, 2 b at the welding and cutting edges of thewelding punch 8, and welding and cut seams are produced.

After that, the film-wrapped products 1 are separated by means of anautomatic separator 11. The residual film remaining is then rolled up12.

As a result of ultrasonically welding the first and second sheets offilm 2 a, 2 b together, very thin, but nevertheless extremely durablewelding seams can be created.

In order to make it possible for the consumer later on to tear open theproducts 1, especially consumer products, it is advantageous to form apull-tab at the outer edges of the product 1. FIG. 3 illustrates afilm-wrapped product 1 of this kind with a pull-tab 13 in a top planview. The pull-tab 13 is formed from portions of the first sheet of film2 a and second sheet of film 2 b projecting at the outer edges of theproduct 1. The first and second sheets of film 2 a, 2 b are preferablystuck together in the region of the pull-tab 13 with an adhesive mass.

FIG. 4 illustrates the film-wrapped product from FIG. 3 in across-sectional view. It is apparent that the product wrapping can betorn open by pulling apart the two portions of the pull-tab 13, i.e. theportions of the first and second sheets of film 2 a, 2 b. The twosections of the pull-tab 13 are releasably stuck together with anadhesive for this purpose.

FIG. 5 illustrates a further embodiment of a film-wrapped product in atop plan view. In one region of an outer edge of the product wrapping, awelding seam or cut line 14 is formed, which runs transversely into awelding seam 15 at the outer edge of the product wrapping. In this way,a breaking point is formed at the pull-tab 13, so that the pull-tab 13can be split into two halves and the product wrapping van then be tornfurther apart along the welding seam 15 at the outer edge.

FIG. 6 illustrates a further embodiment of the film-wrapped product 1,in which a cut line 17 runs transversely across one of the films of theproduct wrapping between two outer edges 16 a, 16 b, which defines abreaking point in the product wrapping. The cut line 17 extends into onepull-tab 13, which abuts the outer edge 16 b of the product wrapping.When the product wrapping is bent over at the cut line 17, it can betorn open and easily opened with the aid of the pull-tab 13.

In a particular embodiment which is not shown, especially in order toproduce prototypes of product wrappings, a pressure roller 18 as shownin FIG. 7, which can be moved in a freely controlled manner, is providedabove the supporting table 7, which pressure roller 18 is guided acrossthe second sheet of film 2 b according to the contours to be welded orcut. The pressure P exerted on the supporting table 7 by the pressureroller 18 via the first and second sheets of film 2 a, 2 b is variabledepending on the requirements to be met by the ultrasonic welding seamor cut seam. The pressure roller 18 can be guided with an X-Y carriage,a robot pivot arm or the like, computer-controlled guidance of thepressure roller 18 being provided.

1. A method of wrapping products in films comprising the steps of:positioning the products on a first sheet of film which is continuouslyadvanced in one transport direction; covering the products with a secondsheet of film, which is continuously advanced in the transport directionand which is aligned plane-parallel to the first sheet of film,ultrasonically welding the first and second films on the outer edges ofeach of the product wrappings and ultrasonically cutting the overlappingfilms at selected positions; forming a pull-tab on an outer edge of theproduct wrapping; forming a welding seam or cut line in the pull-tab,said welding seam or cut line running transversely into a welding seamon the outer edge of the product wrapping; and separating the wrappedproducts or groups of wrapped products.
 2. The method as claimed inclaim 1, wherein the ultrasonic welding and ultrasonic cutting areperformed with a welding punch disposed opposite a supporting table andplane-parallel above one film, the welding punch and supporting tablebeing moved towards one another for ultrasonic welding and ultrasoniccutting.
 3. The method as claimed in claim 2, further comprising thesteps of generating an ultrasonic oscillation on the surface of thesupporting table with a sonotrode device integrated in the supportingtable and pressing the films onto the supporting table in the region ofwelding and cutting edges of the welding punch, wherein welded and cutedges of the wrapped products are an image of the welding and cuttingedges of the welding punch.
 4. The method as claimed in claim 1, whereinat least one film is pre-shaped to receive the products before the stepof positioning the products on the sheet of film.
 5. A device forwrapping products in films, the device comprising: a first conveyormeans for continuously advancing a first sheet of film; a positioningmeans for positioning products on the first sheet of film; a secondconveyor means for covering the products positioned on the first sheetof film with a second sheet of film, which is aligned plane-parallel tothe first sheet of film; a fixed supporting table with an integratedsonotrode arrangement for generating ultrasonic oscillations; anopposing welding punch disposed plane-parallel to the supporting table,said welding punch having welding and cutting edges mounted above thesupporting table such as to move towards and away from the supportingtable; said sheets of film with the products held therebetween beingguided between the supporting table and the welding punch; wherein thewelding and cutting edges of the welding punch are formed in such a waythat a pull-tab is formed on an outer edge of the product wrapping; anda welding seam or cut line is formed in the pull-tab, said welding seamor cut line running transversely into a welding seam on the outer edgeof the product wrapping.
 6. A method of wrapping products in filmscomprising the steps of: positioning the products on a first sheet offilm which is continuously advanced in one transport direction; coveringthe products with a second sheet of film, which is continuously advancedin the transport direction and which is aligned plane-parallel to thefirst sheet of film, ultrasonically welding the first and second filmson the outer edges of each of the product wrappings and ultrasonicallycutting the overlapping films at selected positions; forming a cut linebetween two outer edges of the product wrapping, said cut line runningtransversely across one of the films of the product wrapping; andseparating the wrapped products or groups of wrapped products.
 7. Amethod of wrapping products in films comprising the steps of:positioning the products on a first sheet of film which is continuouslyadvanced in one transport direction; covering the products with a secondsheet of film, which is continuously advanced in the transport directionand which is aligned plane-parallel to the first sheet of film,ultrasonically welding the first and second films on the outer edges ofeach of the product wrappings and ultrasonically cutting the overlappingfilms at selected positions; separating the wrapped products or groupsof wrapped products; wherein the ultrasonic welding and/or ultrasoniccutting are performed with a pressure roller disposed opposite andplane-parallel to the supporting table above one film, said pressureroller being guided across said film according to contours to be weldedand cut, with pressure exerted on the supporting table for ultrasonicwelding and/or ultrasonic cutting.
 8. A device for wrapping products infilms, the device comprising: a first conveyor means for continuouslyadvancing a first sheet of film; a positioning means for positioningproducts on the first sheet of film; a second conveyor means forcovering the products positioned on the first sheet of film with asecond sheet of film, which is aligned plane-parallel to the first sheetof film; a fixed supporting table with an integrated sonotrodearrangement for generating ultrasonic oscillations; an opposing weldingpunch disposed plane-parallel to the supporting table, said weldingpunch having welding and cutting edges mounted above the supportingtable such as to move towards and away from the supporting table; saidsheets of film with the products held therebetween being guided betweenthe supporting table and the welding punch; wherein the welding andcutting edges of the welding punch are formed in such a way that a cutline between two outer edges of the product wrapping is formed that runstransversely across one of the films of the product wrapping.
 9. Thedevice as claimed in claim 8, further including at least one pre-shapingmeans for at least one of the sheets of film such that the products canbe received in indentations in the pre-shaped films.